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Flashcards

Computer Systems Lecture 3: Data Formats

Nisha K Computer Science Inglês 48 flashcards

Computer Systems Lecture 3: Data Formats

Flashcards do conjunto (48)

  1. 1Define analog dataa continuous representation, analogous to the
    actual information it represents.
  2. 2Define digital dataA discrete representation, breaking the information up into separate (discrete) elements and representing those pieces using binary digits
  3. 3Why can't computers use analog dataComputing systems are finite machines. They store a limited amount of information, even if the limit is very big.
    Computer cannot work with analog information, need to digitise the analog information
  4. 4What data format do computers use?All forms of data are stored in binary format
  5. 5What data format do humans use?Uses languages, images and sound
  6. 6What is the purpose of data standards?Implements rules of which data is to be recorded
    Allows communication and sharing of information
  7. 7Give 3 examples of standards Organisations• ISO – International Standards Organization
    • IEEE – Institute for Electrical and Electronics
    Engineers
    • ANSI – American National Standards Institute
  8. 8What standards do alphanumeric daata use?Unicode, ASCII
  9. 9What standards do image (bitmap/raster) use?GIF (graphical image format)
    TIFF (tagged image file format)
    PNG (portable network graphics)
    JPEG (Joint Photographers Expert Group)
  10. 10What standards do image (object/vector use?PostScript, SWF (Macromedia Flash),
    SVG
  11. 11What standards do sound data use@??WAV,
    AVI
    MP3
    MIDI
  12. 12What standards do video data use?Quicktime
    MPEG-2
    MPEG-4
    WMV
  13. 13What is numeric data?Used for mathematical manipulation (+, -, *, /)
    There are two types, integer and real
  14. 14What is alphanumeric data?Characters: b T
    • Number digits: 7 9
    • Punctuation marks: ! ;
    • Special-purpose characters: $ &
    Three standards for representing letters and numbers
    • ASCII – American Standard Code for Information Interchange
    • EBCDIC – Extended Binary-Coded Decimal Interchange
    Code (not used anymore, used to be used in IBM mainframes)
    • Unicode
  15. 15What is ASCIIRepresents text strings e.g. "Hello, world", Latin alphabet, Arabic numbers, punctuation characters,accents
    7-bit code: 128 characters
    • 95 graphic codes (displayable on a console)
    • 33 codes (control features of the console or communications channel)
  16. 16What is the ASCII Reference TableWhat is the ASCII Reference Table
  17. 17Write hello using ASCII tablej
  18. 18What is unicode?A 16 bit format that represented 65,536 characters. It is multilingual
    Defines code for all character based alphabets, ideographs for Chinese, Japanese and Korean
    IS a superset of ASCII
  19. 19What are the different representations of Unicode data?UTF-8: sequence of 8 bit code units which is byte-based and common on the web
    UTF-16: : Sequence of 16-bit code units. Is used by Java and
    Windows.
  20. 20How is colour represented on a computerExpressed as a RGB value (3 numbers that indicate the contribution of each of the 3 primary colours)
    RGB value(255,255,0), maximises red and green creating a bright yellow
  21. 21Define colour depthAmount fo data that is used to represent a colour
  22. 22What is HiColorA 16-bit colour depth, five bits are used for each number in a RGB value, the extra bit is used for transparency
  23. 23What is TrueColorIndicates a 24-bit color depth. Each number is represented using 8 bits
  24. 24Give examples of image dataPhotographs
    Figures
    Icons
    Drawings
    Charts
    Graphs
  25. 25What are bitmap imagesUsed for realistic images with continous variation in shading, colour, shaping e.g. scanned photos or clip art
  26. 26What is raster-graphics/bitmapped formatThe storage of image information on a pixel-by-pixel basis
  27. 27Give examples of who uses it and whyUsed by scanners, digital cameras, video capture devices
    Preferred when image contains lots of detail
    Managed by photo editing software
  28. 28Define resolutionNumber of pixels used to represent a picture
  29. 29What is the monochrome bitmap displayBlack or white
    1 bit per pixel
  30. 30What is the gray scale bitmap displayBlack, white or 254 shades of grey
    1 byte per pixel
  31. 31What are color graphics16 colours, 256 colours or 24-bit true colour (4, 8, 16 bits)
  32. 32How are bitmap images stored?THey are large files
    File size is affected by resolution (amount of detail affecting clarity)
    Levels (number of bits displaying shades of colour)
    Data compression
  33. 33What are GIFSGraphics Interchange Format enabled animated images
    Limited to 8 bit (256) colour images only
    Lossless compression enabled
    Preferred for line drawings, clip art, blocks of solid colour
  34. 34What is JPEGJoint Photographers Expert Group
    Allows 16 million + colours
    Used for highly detailed photographers and paintings
    Uses lossy compression algorithm which can decrease file size and transmission speed by discarding data
    But reduces image resolution
  35. 35What is TIFFTagged Image File Format
    Used in high-quality image processing, particularly in publishing
  36. 36What is BMPBitMaPPred
    Device-independent format for Microsoft Windows environment:
    pixel colors stored independent of output device
  37. 37What is PNGPortable Network Graphics
    Designed to replace GIF and JPEG for Internet applications
    • Improved lossless compression
    • No animation support
  38. 38What are vector images Created by drawing packages or output from spreadsheet data graphs
     Composed of lines and shapes in various colors
     Computer translates geometric formulas to create the graphic
     Storage space depends on image complexity
  39. 39State some properties of vector imagesEasy to move, rotate without losing shape
    Requires less torage than bitmap
    Cannot represent photos or paintings
    Has to be converted to bitmap to be displayed/printed
    Eg. SVG, EPS
  40. 40Compare Bitmap to vector imagesCompare Bitmap to vector images
  41. 41What format is used to represent high quality videos?MPEG-2 allows movie quality images with high compression, needs a lot of processing
  42. 42How is sound digitised?we periodically measure the voltage of the
    signal and record the appropriate numeric value. The process is
    called sampling
  43. 43What are 8 bit, 16 bit and 2 x 16 bits used for8 bit number for radio-quality recording
    16 bit number for high-fidelity recordings
    2 x 16 bits for stereo
  44. 44Name some audio formatsMP3
    WAV
    MIDI
  45. 45What is MP3dominant format for compressing audio data
    • Discards sounds outside human hearing range: lossy compression
    • analyzes the frequency spread and discards info that can’t be heard by humans: lossy compression
    • bit stream is compressed using a form of Huffman encoding to achieve lossless compression
  46. 46What is WAVGeneral-purpose format for storing and reproducing
    small snippets of sound
  47. 47What is MIDI(Musical Instrument Digital Interface): music notation
    system that allows computers to communicate with music
    synthesizers
  48. 48Name different compression methodsRepetition: 0 5 8 7 0 0 0 0 3 4 0 0 0 -->
    0 1 5 8 7 0 4 3 4 0 3
    Pattern substitution: scans data for pattern and makes a dictionary entry for each pattern

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Computer Science FlashCards sobre Computer Systems Lecture 3: Data Formats, criado por Nisha K em 30-12-2017.
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Nisha K
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